Abstract: On the basis of field experiments conducted by authors for a few years, the methods, effect, reduction of crop yield and its reasons for straw mulch in dryland were summarized and analyzed. It was showed that the reduction of crop yield under straw mulch should be paid more attention to although the most of the data showed the remarkable improvement of soil water condition and crop yield under straw mulch. The reasons for yield reduction probably due to the changes of soil water content, soil temperature, fertility and other factors resulted from straw mulch. Further researches are needed. Some suggestions were given for further researches.